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Alevel BiO ;) > osmoregulation and negative feedback > Flashcards

osmoregulation and negative feedback Flashcards

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Biology 101 flashcards
1
Q

define homeostasis

A

the maintenance of internal environment

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2
Q

what is the importance of homeostasis

A
  • enzymes that are sensitive to change in temperature and pH - this therefore avoids denaturing
  • changes to water potential of blood and tissue and tissue fluid may cause cells to shrink or expand
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3
Q

what is positive feedback

A

when a deviation from an optimum causes changes that result in an even greater deviation from the optimum

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4
Q

what is negative feedback

A

changes that return systems back to optimum

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5
Q

what is an ectotherm

A

organisms that gain heat from the environment

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6
Q

what is an endotherm

A

organisms that generate their own heat

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7
Q

what is piloerection

A

where hairs stand on end

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8
Q

what will happen when your body is cold

A

shivering
- piloerection
- increased metabolic rate
- vasoconstriction
- behavioural changes

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9
Q

what happens when you are too hot

A
  • vasodilation
    -sweat
  • pilorelaxation
  • behavioural chnages
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10
Q

what is the function of glucagon

A

glucagon causes liver cells to convert glycogen to glucose which is released into the blood - therefore raising blood glucose levels `

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11
Q

what is the function insulin

A

it will increase the uptake of glucose by cells and its conversion to glycogen and fat

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12
Q

which system do insulin and glucagon work on

A

negative feedback

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13
Q

what happens if temp of the blood is too high

A

thermoreceptors in the hypothalamus send more impulses to cool down

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14
Q

define gluconeogenesis

A

conversion of non-carbohydrates into glucose when glycogen supply is exhausted - usually amino acids or glycerol

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15
Q

define glycogenesis

A

conversion of glucose into glycogen

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16
Q

define glycogenolysis

A

breakdown of glycogen to glucose via hydrolysis

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17
Q

where does gluconeogenesis, glycogenesis and glycogenolysis occur

A

in the liver

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18
Q

where are the receptors that detect blood glucose levels located

A

islets of Langerhans

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19
Q

what do alpha cells secrete

A

glucagon

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20
Q

what do beta cells secrete

A

insulin

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21
Q

what do the islets of langerhan contain

A

alpha and beta cells

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22
Q

what happens when blood glucose levels are too slow

A

alpha and beta cells in the islets of Langerhan will detect this stimuli
the alpha cell will stop secreting insulin.
the beta cell containing glucagon will be secreted and will bind to the cell surface membrane of liver cells. this binding will stimulate enzymes associated with glycogenolysis and gluconeogenesis
glucose is released from the cells and blood glucose concentration is increased

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23
Q

describe the mechanism of insulin

A

beta cells detect the increase in blood-glucose levels
- glucose moves into beta cells via facilitated diffusion
- this will cause insulin containing vesicles to move towards the cell surface membrane where they release insulin into the capillaries.
- insulin binds to specific receptors of target cells #.
this will stimulate the cells to add more glucose transporter proteins to their cell surface membrane which increases the cells permeability to glucose
- rate of fac d into the cells increases lowering blood glucose levels
- insulin binding to receptor on liver cells causes the increase of uptake of glucose in the liver by stimulating glycogenesis which converts glucose to glycogen. this will lower blood glucose levels in the liver which will help to maintain a conc grad between capillaries and liver cells

24
Q

what is type 1 diabetes

A

where the body does produce enough insulin

25
Q

what is the result of type 2 diabetes

A

it is due glycoprotein receptors being unresponsive to insulin

26
Q

what is the name of homeostatic control of water potential

A

osmoregulation

27
Q

what is the function of the fibrous capsule

A

a protective membrane around the kidney

28
Q

what is the cortex
kidney context

A

a lighter coloured outer made up of renal capsules, convuluted tubules and blood vessels

29
Q

what is the medulla

kidney context

A

a darker coloured inner region made of loops of henele, collecting ducts and blood vessels

30
Q

what the function of renal pelvis

A

a funnel shaped cavity that collects urine into the ureter

31
Q

what si the function of the ureter

A

a tube that carries urine tot he bladder

32
Q

what is the function renal artery

A

supplies the kidney with blood from heart via aorta

33
Q

what is the function of the renal vein

A

returns blood to the heart via the vena cava

34
Q

what is the function of the renal capsule

sometimes called bowmans capsule

A
  • the closed end at the start of the nephron. it is cup shaped and surrounded by a mass of blood capillaries called the glomerulus - the inner layer of the renal capsule is made up of podocytes
35
Q

what is the proximal convoluted tubule

A

a series of small loops surrounded by blood capillaries. its walls are made of epithelial cells which have microvilli for large SA

36
Q

what components make up the nephron

A
  • proximal convoluted tubules
  • renal capsule
    -loop of Henele
  • distal convoluted tubule
  • collecting duct
37
Q

what is the distal convoluted tubule

A

a series of loops surrounded by blood capilliaries. its walls are made of epithelial cells, but it is surrounded by fewer capillaries than the proximal tubule

38
Q

what id the function of the collecting duct

A

a tube into which a number of distal convoluted tubules from a number of nephrons empty. it is lined with epithlal cells

39
Q

what is the afferent arteriole

A

a tiny vessel that ultimately arises from the renal artery and supplies the nephron with blood

40
Q

what si the glomerulus

A

a many branched knot of capillaries from fluid is forced out.

41
Q

what is the efferent

A

a tiny vessel that leaves the renal capsule

42
Q

what is the difference in the efferent and the affreent

A

the efferent has a smaller diameter - therefore has a pressure

43
Q

how does the nephron carry out osmoregulation

A
  • the formation of glomerulus by ultrafiltration
  • the reabsorption of glucose and water by the PCT
    maintance of a sodium ions in the medulla by the loop henle
    • reabsorbed of water by the distal convoluted and collecting ducts
44
Q

what is a podocyte

A

a tiny finger like projection with gaps in between them

45
Q

where does the ascending limb of the loop of henle go

A

drains into the Distal convoluted tubule

46
Q

where does the descending limb of the loop of henle g

A

Medulla

47
Q

what is the function of the loop of Henle

A

allows Na+ and Cl- to be transferred from the ascending limb to the descending limb. the overall effect is to increase the concentration of salt in filtrate therefore there will be a low water potential

48
Q

which hormone is the permeability of the DCT and the collecting duct controlled by

A

ADH

49
Q

what is good about the loop of Henle

A

the water potential set up by the loop of Henle allows water to be absorbed along the whole length of the collecting duct

50
Q

REMEMBER

A

water is absorbed into the blood not just the surrounding tissue

51
Q

how is the PCT adapted for max reabsorption

A
  • folded membrane to give large surface area
  • lots of membrane proteins for facilitated diffusion
    -lots of ribosomes to make such proteins
  • lots of mitochondria to provide the ATP for protein synthesis and active transport which could be used to reabsorb the molecule
52
Q

EXIT EFFERENT
leAve afferent

A
53
Q

what is an aquaporin

A

channel proteins that form pores in the membrane facilitating transport of water molecules

54
Q

which molecules cannot be forced out o f the capillary in ultrafiltration

A

blood cells and proteins - they are too large

55
Q

what is ultrafiltration

A

due to differences in hydrostatic pressure in the efferent and afferent arteriole. water urea, mineral ions and glucose are squeezed out of the capilliary and into the renal capsule

56
Q
A
57
Q
A

Alevel BiO ;) (32 decks)

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